Commit 5a2553a7b64c48569f883de424f1747045bcdc0f
2019-08-07T14:44:12
Vulkan: Emulate subgroup ops in seamful cubemap emulation Where subgroup ops are not available, they are emulated as such: Code with subgroup ops: float lH = subgroupQuadSwapHorizontal(layer); float lV = subgroupQuadSwapVertical(layer); float lD = subgroupQuadSwapDiagonal(layer); bool isHelperH = subgroupQuadSwapHorizontal(gl_HelperInvocation); bool isHelperV = subgroupQuadSwapVertical(gl_HelperInvocation); if (gl_HelperInvocation) { layer = !isHelperH ? lH : !isHelperV ? lV : lD; } Emulated code: float nonHelperLayer = gl_HelperInvocation ? 0.0 : layer; float lH = abs(dFdxFine(nonHelperLayer)); float lV = abs(dFdyFine(nonHelperLayer)); float lD = abs(dFdxFine(lV)); float isHelperDiffH = abs(dFdxFine(float(gl_HelperInvocation))); bool isNonHelperH = isHelperDiffH > 0.5; float isHelperDiffV = abs(dFdyFine(float(gl_HelperInvocation))); bool isNonHelperV = isHelperDiffV > 0.5; if (gl_HelperInvocation) { layer = isNonHelperH ? lH : isNonHelperV ? lV : lD; } Both paths are supported as on nvidia devices the emulated code misbehaves. This change therefore effectively only enables seamful cube map emulation on Android where subgroup operations are not supported. Bug: angleproject:3243 Bug: angleproject:3732 Change-Id: I9664d9760756758748183eb121c626f176789f3a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1742222 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>